1. Field of the Invention
The present invention relates generally to setting of magnification of a copying machine and, more specifically, to a portion for setting arbitrary copying magnification using a slide bar.
2. Description of the Prior Art
A magnification setting portion of a conventional copying machine is disclosed in, for example, Japanese Laid-Open Patent Application No. 113216/1985 entitled "Image Processing Apparatus". FIG. 1 shows an appearance of an operating portion of a conventional copying machine. The conventional operating portion comprises, for setting the magnification of the copying machine, a magnification rate displaying portion 34 for displaying the magnification rate, an equal scale magnification setting key 39, a prescribed scale magnification setting key 40, an equal scale magnification displaying portion 36, a prescribed scale magnification displaying portions 37a to 37c, a variable scale magnification setting lever 35 and a variable scale magnification copying mode display 38. Numerals 41 written on the upper portion of the variable scale magnification setting slide key show the graduation of the copying magnification. The magnification setting portion of a conventional copying machine comprises a number of levers and keys for setting variable scale magnification and prescribed scale magnification. Therefore, for a user, it is troublesome to select keys. For the copying machine, there is a problem that large area of the operation panel are occupied by keys for setting magnification. For example, in the above described prior art, the area of the magnification setting portion is about 1/3 of the total area of the operation panel.
Meanwhile, the prescribed scale magnification and variable scale magnification can be set merely by a slide bar in order to reduce the occupied area on the operation panel. In this case, however, the user must pay close attention in setting prescribed scale magnification. If the position of the slide bar is shifted a little, the magnification rate changes.